We have studied in search of useful derivatives of a known compound, forphenicine having the following structure: ##STR3## Forphenicine is a known substance which was first isolated from the culture broth of a strain of actinomycetes by H. Umezawa et al. and which is useful as a strong inhibitor of alkaline phosphatase (Japanese patent application pre-publication "Kokai" No. 116685/75, Journal of Antibiotics Vol. 31, No. 3, pp. 244-246 and Vol. 31, No. 5, pp. 483-484 (1978)).
As a result of our extensive studies, we have now succeeded in producing a new compound of the structural formula: ##STR4## and its salts and hydrates. We have further found that these compounds have immunopotentiating activity and are thus useful as an immunopotentiator for enhancing the immune response in living animals and humans. It is also found that the new compound (I) of this invention is more stable than forphenicine and upon oral administration exhibits a higher activity than forphenicine.
An object of this invention is to provide new compounds which exhibit immunopotentiating activities. Another object of the invention is to provide processes of producing these new, useful compounds. Further object of the invention is to provide an immunopotentiator comprising these compounds.
Other objects and utilities of the invention will become apparent from the following descriptions.